Must Be ...

Because pterosaurs were so much larger than today's flying animals, one must conclude that our atmosphere was much denser then. And  how could this be? One explanation is that our atmosphere is getting thinner. But the opposite seems true ... see Science Magazine Article.

Thus, our atmosphere then must have been infused with many more carbon dioxide and other complex (heavier) molecules such as methane and water vapor.

Therefore, if life flourished then, we must have far more latitude for changes to our current atmospheric mix than climate scientists, like Al Gore, give us credit for.